Superconducting circuits with reduced microwave absorption

Abstract

Provided are superconducting circuits, methods of operating these superconducting circuits, and methods of determining processing conditions for operating these superconducting circuits. A superconducting circuit includes a superconducting element, a conducting element, and a dielectric element disposed between the superconducting element and the conducting element. The conducting element may be another superconducting element, a resonating element, or a conducting casing. During operation of the superconducting element a direct current (DC) voltage is applied between the superconducting element and the conducting element. This application of the DC voltage reduces average microwave absorption of the dielectric element. In some embodiments, when the DC voltage is first applied, the microwave absorption may initially rise and then fall below the no-voltage absorption level. The DC voltage level may be determined by testing the superconducting circuit at different DC voltage levels and selecting the one with the lowest microwave absorption.

What is claimed is: 
     
       1. A method comprising:
 providing a superconducting circuit, 
 wherein the superconducting circuit comprises a superconducting element, a conducting element, and a dielectric element disposed between the superconducting element and the conducting element; and 
 applying a direct current (DC) voltage between the superconducting element and the conducting element; 
 wherein the dielectric element comprises structural defects; and 
 wherein the applying of the DC voltage reduces a microwave absorption of the dielectric element. 
 
     
     
       2. The method of  claim 1 , wherein applying the DC voltage initially increases the microwave absorption of the dielectric element; and wherein the microwave absorption of the dielectric element subsequently decreases. 
     
     
       3. The method of  claim 1 , wherein a value of the DC voltage is selected based on one or more of a type of the structural defects and a distribution of the structural defects within the dielectric element. 
     
     
       4. The method of  claim 1 , wherein the DC voltage is applied for a period of time prior to operating the superconducting element. 
     
     
       5. The method of  claim 1 , wherein the conducting element comprises one of an additional superconducting element, a resonating element, or a conducting casing. 
     
     
       6. The method of  claim 1 , wherein the dielectric element comprises at least one of silicon oxide, amorphous silicon, or aluminum oxide. 
     
     
       7. The method of  claim 1 , wherein the DC voltage is between about 0.005 Volts and 5 Volts. 
     
     
       8. The method of  claim 1 , wherein the dielectric element has a thickness of between about 30 nanometers and 10 millimeters. 
     
     
       9. The method of  claim 1 , wherein the conducting element is grounded. 
     
     
       10. The method of  claim 1 , wherein the applying of the DC voltage comprises a voltage sweep. 
     
     
       11. A superconducting circuit comprising:
 a superconducting element; 
 a conducting element; 
 a dielectric element; and 
 a voltage controller,
 wherein the dielectric element is disposed between the superconducting element and the conducting element; 
 wherein the dielectric element comprises structural defects; and 
 wherein the voltage controller is connected to apply a direct current (DC) voltage between the superconducting element and the conducting element at least when the superconducting element is operating. 
 
 
     
     
       12. The superconducting circuit of  claim 1 , wherein the voltage controller is communicatively coupled to a system controller used to operate a superconducting circuit. 
     
     
       13. The superconducting circuit of  claim 1 , wherein the conducting element comprises one of an additional superconducting element, a resonating element, or a conducting casing. 
     
     
       14. The superconducting circuit of  claim 1 , wherein the dielectric element comprises amorphous silicon, silicon oxide, or aluminum oxide. 
     
     
       15. The superconducting circuit of  claim 1 , wherein the dielectric element has a thickness of between about 30 nanometers and 10 millimeters. 
     
     
       16. A method comprising:
 providing a superconducting circuit, wherein the superconducting circuit comprises a superconducting element, a conducting element, and a dielectric element disposed between the superconducting element and the conducting element; 
 applying a first level of direct current (DC) voltage between the superconducting element and the conducting element; 
 determining a first level of microwave absorption in the dielectric element corresponding to the first level of the DC voltage; 
 applying a second level of the DC voltage between the superconducting element and the conducting element; 
 determining a second level of microwave absorption in the dielectric element corresponding to the second level of the DC voltage; and 
 selecting a level of the DC voltage corresponding to a lowest level of microwave absorption; 
 wherein the dielectric element comprises structural defects. 
 
     
     
       17. The method of  claim 16 , further comprising comparing the lowest level of microwave absorption to a baseline level of microwave absorption observed when no DC voltage is applied between the superconducting element and the conducting element. 
     
     
       18. The method of  claim 16 , wherein the microwave absorption reaches a steady state after applying the DC voltage. 
     
     
       19. The method of  claim 16 , wherein the dielectric element comprises amorphous silicon, silicon oxide or aluminum oxide. 
     
     
       20. The method of  claim 16 , wherein the dielectric element has a thickness of between about 30 nanometers and 10 millimeters.